A process for the preparation of quaternary diesters is disclosed by EP-A-21 431. A drawback to the known process described in this document is that it is a comparatively elaborate two-step process, with a secondary amine of the formula R.sub.1 --NH--R.sub.2 being converted by addition thereto of an equimolar amount of monochloroacetate ester in the first step, followed by separation of the formed reaction product and addition of a further equivalent amount of monochloroacetate ester in a second step.
The present invention overcomes the deficiencies of the prior art and provides a highly simplified, one-step process for the preparation of quaternary diesters.